Vacuum tube



$.RUBEN I VACUUM TUBE July 28, 1931.

Filed Feb. 8, 1930 2 Sheets-Sheet Hu llllll ll HUIIIIII I I I.

f-Jvwzmtoz MEL RUBEN w W M W July 28, 1931. s, RUBEN 1,815,931

VACUUM TUBE Filed Feb. 8. 1930 2 Sheets-Sheet 2 Flt-3.5,, 1

I I 1 I a -7 i 6 6 A SE J i z L "E rib ,2,

:1 .2; iii 1 :H I: l. a

avwe'ntoz SAMUEL RUBEN 32, 1M ewrmq W4 W Patented July 28, 193 1 UNITED STATES PATENT OFFICE SAMUEL imam, on NEW "zonx, 1w. 1., assmuon 'ro RUBEN TUBE conrm". or

' ENGLEWOOD, NEW JERSEY, A conrona'rron or nnmwm VACUUM TUBE pplication file Iebruary 8, 1880. Serial No. 428,828. U D

This invention relates 'to an improvement in vacuum tubes and more particularly it relates to a vacuum tube for the amphlication of electrical oscillations. An object of this invention is the pro'yision of a vacuum tube having a. high amplification factor with a large power output.

In general, my invention consists of a vacuum tube employing multiple sets of elements so arranged that one set of elements is connected to the input circuit, the other to an output circuit and so connected that the second set produces an amplified response to the energy applied to the input electrodes of the cooperating set of elements. The second set, such as the cathode, grid and plate, are not directly connected to the input circuit as are the elements in tubes of the prior art, but are indirectly coupled through the output circuit of o the first set of elements. As applied herein, the term first set of elements refers to those elements, as the cathode, grid and plate, which are directly coupled to the input circuit.

5 By the use of a tube of the design described, it has been possible to obtain an energy output which is undistorted and of greater density. For a better understanding of the invention, reference is made to the aco compa zryi ng drawings illustrating an embodiment thereof, in which Fig. 1 represents a vacuum tube having parts of the plate elements so cut away as to better show its construction; Fig. 2 illustrates a section plan 5 view of the tube at 2-2; Fig. 3, represents a section view of the two cathodes angl of the heater element, together with the in ulation block separating the cathodes; FigA shows a circuit in which the tube device is connected;

0 Fig. 5 shows the same tube device with two grids in place of one, in the arrangement of the upper set of elements and Fig. 6 is a section plan view of this device taken at 6-6.

Referring more particularly to Fig. l, 1

5 represents an evacuated glass envelope, 2, the

hairpin heater element coated with a refractory insulating oxide; 3, an oxide coated cylindrical nickel cathode supported by conductor wire 3,, passing through glass rod 6,

0 from which latter a hook suspends heater element 2. {The lower cathode is represented by 3. which is insulated from the upper cathod e by insulating member 3.. The upper grid is represented by 4, sup orted by rods 4 These rods are suspended From glass rod 6 and one of the supporting rods, 4 has a terminal outlet at 4.. The upper plate 5, is supported by rods 5., and 5., the latter having a terminal at 5.. The lower cathode 3 is supported by rod 3. having a terminal at 3 the m lower grid 4., supported by rods 4., is con nected by conductor 4 with the upper cathode. The lower plate element 5., is supportectl 5by-rods 5. and 5. with a terminal outleta Corresponding elements in Figs. 1, 2. 3 and: 4 are indicated by like numerals.

In Fig. 4 at B is a battery for biasing the cathode negative in respect/to the heater 'ele-' 'ment which latter is heated from transfbrmer H. At B is a source of plate potential forf obtaining the plate current C, being a by-pass condenser in the circuit with a translatingf device T. B is a battery or source of potential for maintaining the input grid negative with respect to the cathode 3. The-"other ele-.- ments of the circuit correspond to those in, the usual arran 'ement of similar circuits.

Referring to Figs. 5 and ,6, the several elements there illustrated correspond with those bearing like numerals in Figs. 1 and 2, 0 except that the additional grid 7 is interposed between grid 4- and anode 3. That grid is supported-by rods 7 and has a terminal outlet at 7 This is connected in the circuit as is common practice in circuits employing a screen grid tube. 1

In the operation of the device illustrated by Fig. 1, when thefilament 2 isheated, indirectly heating cathodes 3 and 3., they emit electrons assisted by the plate potential from batteryB This causes a plate current to flowv between ti? upper cathode and the upper plate and between the lower cathode and the lower grid. In otherwords, there are two electron discharges; from the upper cathode to theupper plate, and from the ower cathode to the lower grid, this being equivalent to two electron'discharges in series and a single plate potential. The other and higher density discharge is between the lower cathode and the lower plate. As the lower grid is in the current discharge circuit of the upper electron dischar and as its potential is overned by the density of the up r electron ischarge, any modulation of t 's electron discharge by the control gr1d having such a form as to give a high am lification constant, causes a variation in the higher density lower electron discharge. If the electron emission from the upper cathode is varied by modulation by the change of potential of the upper or input grid by nnpressed oscillations the positive potential of the lower grid varies accordingly, and as this potential controls the electron emlssion between the lower cathode and the lower plate, an amplified current change will occur in the output circuit. In a preferred form of this device the upper gr1d is made with a large number of turns to allow a high amplification constant, and is initially negative y biased so as to reduce the positive potential onthe lower grid. The

lower grid can be coarser or have fewer turns,-

so as to offer a low impedance path between lower cathode and its cooperate plate or anode. The output from the input tube circuit can be tuned to radio frequency if desired. The operation of the input circuit and the other commonly employed elements shown is so well known in the art that descri tion is considered unnecess ere radio fr'equen ampli cation is especially desired a shiel g or screen grid may be introduced between t e plate and the control. grid. The control grid and the plate are such as are commonly used with the screen grid type of tube to reduce the efiects with mter-element coupling.

It is obvious that t e relative positions of the sets can be varied.

What I claim is 1. A vacuum tube comprising an envelgpe containing a cathode, a grid and a plate ament, another cathode, grid and plate element, a heater element for indirectl heating said cathodes, said second mentione grid being directly connected with the first mentioned cathode.

2. A vacuum tube comprising an envelope containing a cathode, a grid and a plate element, another cathode, gridand .plate element, a heater element for indirectly said cathodes, being directl connected with the first mentioned catho e, and means for electrically insulating the first mentioned cathode from the second mentioned cathode.

vacuum tube comprising an envelope containing a cathode, a grid and a plate element, another cathode, grid and late element, a heater element for indirect y heating said cathodes, ing a higher (pedance than the second mentioned grid, sai

second mentioned grid being heating said second mentioned gri the first mentioned grid ofiernames! III 

